Background, i have a '91 W124 300E that used to see regular driving but then became a backup car that sat most of the time. It got harder and harder to start when cold each time until it eventually just wouldnt start at all. If you poured a little gas down its throat it would start and run for a few seconds and die. Over a period of a year or so, I went through all of the checks that are recommended on the forums for this problem and replaced several parts with no joy. I eventually replaced the EHA simply because I'd gotten one of a 300e at the salvage along with several other parts and THAT is what fixed it. The old one looked fine and had been replaced about 4 years prior.
The strange thing is, the very next morning, the car wouldn't start again. I replaced the EHA again with another one I had from the salvage and it started and ran fine once again.
I had been running ethanol fuel in the vehicle this whole time and it had gotten a bit stale. There were no signs of dirt or contamination in the EHA or the main filter. Is it possible for ethanol fuel to take out an EHA?